A gas barrier property is imparted to containers used in foods, industrial products, and the like in many cases in order to prevent deterioration of contents due to incorporation of gas such as oxygen from the outside and to prevent volatilization of active ingredients and the like from the contents. In order to impart the gas barrier property to a container main body, when the container is made of a resin, it is known to provide a multi-layer structure by forming a layer made of a gas barrier material such as a gas barrier resin or an aluminum foil. In addition, it is also known to impart the gas barrier property by dispersing a gas barrier resin in a layered form in polyolefin or the like which is a main component of a resin container. Furthermore, when a high gas barrier property is required, containers made of glass are used in some cases.
Meanwhile, a cap for closing the mouth portion of the container has a small surface area, so that the gas barrier property is not imparted in many cases. However, since a high gas barrier property has been recently required for a container in some cases, it has been studied to impart a gas barrier property to a cap as well. For example, PTL 1 discloses a container cap in which a m-xylylene group-containing polyamide as a gas barrier resin is dispersed in a layered form in a polyolefin as a main component of a resin cap.